Liquefaction behavior of fiber-reinforced calcareous sand under cyclic simple shear tests

Fiber-reinforcement presents a promising approach to mitigate the liquefaction issues commonly associated with calcareous sand as a construction fill material. However, the essential feasibility in the liquefaction resistance provided by fiber inclusion in calcareous sand still require thorough evaluation. In light of this, this paper presented an experimental study on the cyclic behavior of calcareous sand through a series of unidirectional undrained simple shear tests. The effects of fiber content, fiber length, and cyclic stress ratio (CSR) on the liquefaction resistance of fiber-reinforced calcareous sand were studied. The results indicate that incorporating fibers significantly boosts the liquefaction resistance of calcareous sand, and longer fibers further enhance the resistance by more effectively interlocking with sand particles. While increased cyclic stress ratio reduces liquefaction resistance, fibers can slow the rate of shear strain development when the CSR is low. Additionally, fiber inclusion helps mitigate stiffness degradation, although a high cyclic stress ratio accelerates the degradation. Based on experimental data, a suitable fiber content and fiber length for practical design was suggested. Furthermore, a pore pressure prediction model considering the effects of fiber content and CSR was developed, which can effectively predict the development of pore pressure in fiber-reinforced calcareous sand under a variety of engineering construction situations.